A program to develop lasers suitable for irradiating externally supplied chromophores (dyes) in tissue using selective photothermolysis (SP) is proposed. SP allows precise target specificity in vivo by color selectivity, and spatial selectivity does not depend on focusing but instead depends on time resolution. Large tissue volumes can be treated simultaneously and non-target tissue spared. The lasers to be developed will be compatible with existing FDA approved sterile dyes. Studies will be conducted on animals for the treatments of senile macular degeneration (SMD), hemostasis of gastrointestinal bleeding, and tumor cell killing by the irradiation of dyes conjugated to monoclonal antibodies. The lasers will emit in the near infrared and will have pulse durations corresponding to target size--submicrosecond for cells and milliseconds for vessels. The emphasis will be on the treatment of SMD, the leading cause of legal blindness in the United States. Most of the eyes with SMD go into blindness because of choroidal neovascularization. SP promises to be superior to existing photocoagulation techniques for treating SMD. If feasibility is proven on animals in Phase 1, the treatment of human subjects will be the focus of a Phase II grant, and Phase III will result in a commercial product.